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Trac macros extend the Trac engine with custom functionality. Macros are a special type of plugin and are written in Python. A macro inserts dynamic HTML data in any context supporting WikiFormatting.
The macro syntax is [[macro-name(optional-arguments)]].
WikiProcessors are another kind of macros. They are typically used for source code highlighting, such as !#python or !#apache and when the source code spans multiple lines, such as:
```#!wiki-processor-name
...
## Using Macros
Macro calls are enclosed in double-square brackets `[[..]]`. Like Python functions, macros can have arguments, which is then a comma separated list within parentheses `[[..(,)]]`.
### Getting Detailed Help
The list of available macros and the full help can be obtained using the MacroList macro, as seen [#AvailableMacros below].
A brief list can be obtained via `[[MacroList(*)]]` or `[[?]]`.
Detailed help on a specific macro can be obtained by passing it as an argument to MacroList, e.g. `[[MacroList(MacroList)]]`, or, more conveniently, by appending a question mark (`?`) to the macro's name, like in `[[MacroList?]]`.
### Example
A list of the 3 most recently changed wiki pages starting with 'Trac':
| Wiki Markup | Display |
|---|---|
```#!td
```
[[RecentChanges(Trac,3)]]
```
```#!td style="padding-left: 2em;"
[[RecentChanges(Trac,3)]]
|-----------------------------------
```#!td
```
[[RecentChanges?(Trac,3)]]
```
```#!td style="padding-left: 2em;"
[[RecentChanges?(Trac,3)]]
|-----------------------------------
```#!td
```
[[?]]
```
#!td style="padding-left: 2em"#!html
[[Image]]
Embed an image in wiki-formatted text.
The first argument is the file, as in
[[Image(filename.png)]]
[[InterTrac]]
Provide a list of known
InterTrac prefixes.
[[InterWiki]]
Provide a description list for the known
InterWiki prefixes.
[[KnownMimeTypes]]
List all known mime-types which can be used as
WikiProcessors.
Note that the following list will only contain the macro documentation if you've not enabled -OO optimizations, or not set the PythonOptimize option for [wiki:TracModPython mod_python].
[[MacroList]]
The [Trac Hacks] site provides a wide collection of macros and other Trac TracPlugins plugins contributed by the Trac community. If you are looking for new macros, or have written one that you would like to share, please visit that site.
Macros, like Trac itself, are written in the Python programming language and are developed as part of TracPlugins.
For more information about developing macros, see the [trac:TracDev development resources] on the main project site.
Here are 2 simple examples showing how to create a Macro. Also, have a look at [trac:source:tags/trac-1.0.2/sample-plugins/Timestamp.py Timestamp.py] for an example that shows the difference between old style and new style macros and at the [trac:source:tags/trac-0.11/wiki-macros/README macros/README] which provides more insight about the transition.
To test the following code, save it in a timestamp_sample.py file located in the TracEnvironment's plugins/ directory.
```#!python
from datetime import datetime
from genshi.builder import tag
from trac.util.datefmt import format_datetime, utc
from trac.wiki.macros import WikiMacroBase
class TimeStampMacro(WikiMacroBase):
"""Inserts the current time (in seconds) into the wiki page."""
revision = "$Rev$"
url = "$URL$"
def expand_macro(self, formatter, name, text):
t = datetime.now(utc)
return tag.strong(format_datetime(t, '%c'))
### Macro with arguments
To test the following code, save it in a `helloworld_sample.py` file located in the TracEnvironment's `plugins/` directory.
```#!python
from genshi.core import Markup
from trac.wiki.macros import WikiMacroBase
class HelloWorldMacro(WikiMacroBase):
"""Simple HelloWorld macro.
Note that the name of the class is meaningful:
- it must end with "Macro"
- what comes before "Macro" ends up being the macro name
The documentation of the class (i.e. what you're reading)
will become the documentation of the macro, as shown by
the !MacroList macro (usually used in the WikiMacros page).
"""
revision = "$Rev$"
url = "$URL$"
def expand_macro(self, formatter, name, text, args):
"""Return some output that will be displayed in the Wiki content.
`name` is the actual name of the macro (no surprise, here it'll be
`'HelloWorld'`),
`text` is the text enclosed in parenthesis at the call of the macro.
Note that if there are ''no'' parenthesis (like in, e.g.
[[HelloWorld]]), then `text` is `None`.
`args` are the arguments passed when HelloWorld is called using a
`#!HelloWorld` code block.
"""
return 'Hello World, text = %s, args = %s' % \
(Markup.escape(text), Markup.escape(repr(args)))
Note that expand_macro optionally takes a 4^th^ parameter args. When the macro is called as a [WikiProcessors WikiProcessor], it is also possible to pass key=value [WikiProcessors#UsingProcessors processor parameters]. If given, those are stored in a dictionary and passed in this extra args parameter. In the other case, when called as a macro, args is None. (since 0.12).
For example, when writing:
```#!HelloWorld style="polite" -silent verbose
<Hello World!>
```#!HelloWorld
[[HelloWorld(<Hello World!>)]]
One should get:
Hello World, text = <Hello World!>, args = {'style': u'polite', 'silent': False, 'verbose': True}
Hello World, text = <Hello World!>, args = {}
Hello World, text = <Hello World!>, args = None
Note that the return value of expand_macro is not HTML escaped. Depending on the expected result, you should escape it yourself (using return Markup.escape(result)) or, if this is indeed HTML, wrap it in a Markup object (return Markup(result)) with Markup coming from Genshi (from genshi.core import Markup).
You can also recursively use a wiki Formatter (from trac.wiki import Formatter) to process the text as wiki markup:
```#!python
from genshi.core import Markup
from trac.wiki.macros import WikiMacroBase
from trac.wiki import Formatter
import StringIO
class HelloWorldMacro(WikiMacroBase):
def expand_macro(self, formatter, name, text, args):
text = "whatever '''wiki''' markup you want, even containing other macros"
# Convert Wiki markup to HTML, new style
out = StringIO.StringIO()
Formatter(self.env, formatter.context).format(text, out)
return Markup(out.getvalue())
```
